UNCTAD's Series on International Investment Agreements analyses the key concepts of core IIA provisions. The "First-generation Pink Series" or "Series One" (1999-2005) sought to help countries participate as effectively as possible in international investment rulemaking. The "Sequels" or "Series Two" update and complement this Series analysing how key issues in IIA provisions have evolved, particularly focusing on treaty practice and arbitral decisions. In line with UNCTAD's mandate the Sequels analyse the development impact of IIA provisions and their respective formulations, and give policy options that strengthen the sustainable-development aspect of IIAs. Both generations represent a standard reference tool for IIA negotiators, policymakers, the private sector, academia and other stakeholders.